If Krauthammer thinks it’s in U.S. interests for this pipeline to bring tar sands oil to the Gulf coast for shipment overseas, then let him urge Congress to enact a carbon tax to subject tar sands oil to a carbon tax. When the oil enters our country, Canadian producers would pay US carbon taxes reflecting the environmental cost of using that oil.

Then Congress can be the heroes by making the carbon tax revenue-neutral and rebating it to American households. The carbon tax would spur U.S. development of clean energy at cheap prices, and the household rebate would help Americans cope with climate-change related price increases.

Also, President Obama wouldn’t be able to use climate change as a reason to reject the pipeline, and Republicans wouldn’t be able to complain that he is dragging his feet on Keystone and issuing too many EPA regulations.